1. Field of the Invention
The present invention relates to a method for manufacturing a liquid crystal display device, in particular, to a method for manufacturing a plastic liquid crystal display device.
2. Description of the Related Art
A liquid crystal display device generally has a configuration where a pair of substrates which are opposed to each other with a predetermined gap and have electrodes for forming a terminal and display electrodes, are bonded via a sealing material to each other at a bonding region that is provided along an outer periphery of the substrates, a liquid crystal is sealed in a space enclosed by the substrates and the sealing material to form a display part, and a terminal part is provided outside of the layer of the sealing material.
In the terminal part, electrodes to be used as terminals are formed on only one of the substrates, namely no electrodes to be used as terminals are formed in a part of the other substrate, opposite to the terminals, and therefore the part needs to be removed. This part to be removed is called removal part and a process for removing the removal part is called a terminal exposure process.
In the case where the liquid crystal display device uses substrates made of glass, the removal of the removal part can be carried out by drawing a dividing line with a diamond cutter or the like on the upper and lower sides of the substrates under the condition that the pair of the substrates are bonded to each other, and by dividing the pair of the substrates simultaneously with the added pressure along the dividing line, which is not such a difficult process.
In the case of substrates made of thermosetting resin having a thickness of approximately 0.4 mm, the removal part is removed by dividing the substrates with a highly precise blade rotating at high speed (hereinafter referred to as a dicing method) as proposed in the Japanese Unexamined Patent Publication JP-A 5-45617 (1993). To remove the removal part, the substrates are remained uncut by a predetermined thickness, which is then torn off to be removed. The removal part can be removed comparatively easily by tearing off, since the thermosetting resin is hard and rigid.
On the other hand, in the case where the liquid crystal display device uses substrates made of thermoplastic resin, having a thickness of approximately 0.1 mm, a method is proposed for punching out the removal part before the pair of substrates are bonded to each other. In this method, a flash may be generated on the orientation film when the fitting for punching out is pulled away from the substrates in the case where the punching-out is carried out from the side of the orientation film, and the stage or the like contacts the orientation film too closely, which is not preferable because a defective orientation may be caused, in the case where the punching-out is carried out from the opposite side of the orientation film. However, the substrates have a thickness of approximately 0.1 mm, this affect of the flash is small.
In the case where the liquid crystal display device uses substrates made of thermoplastic resin having a thickness larger than approximately 0.2 mm, however, the affect of the flash described above becomes larger, which causes improper sell thickness and makes the display quality worse, therefore the method for punching out the removal part can not be employed.
Compared to thermosetting resin, thermoplastic resin such as PES (polyether sulfone) or PC (polycarbonate) is more flexible and have stronger tensile strength, which makes it difficult to employ the tearing-off method as described in the above. At this time, in the case where the removal part is forced to be removed, the sealing material adhering the pair of substrates may be pealed off from the substrates. In particular, in the case where the liquid crystal material is infiltrated into the terminal part when the liquid crystal material is injected, the pair of substrates may be contacted closely via the liquid crystal material, which makes it more difficult to remove the removal part.
An object of the invention is to provide a method for manufacturing a liquid crystal display device and an apparatus for removing a removal part from a liquid crystal display device, capable of easily removing the removal part even in a liquid crystal display device using substrates made of thermoplastic resin.
The invention provides a method for manufacturing a liquid crystal display device comprising the steps of:
bonding a first substrate on which terminals and display electrodes are formed and a second substrate on which display electrodes are formed, via a sealing material to each other at a bonding region which is provided along an outer periphery of the substrates so as not to surround the terminals, so that the display electrodes face each other;
forming a display part by injecting a liquid crystal material in a space enclosed by the sealing material and the substrates;
providing a half cut line along a border of a removal part which is a part of the second substrate and faces the terminal on a part of the first substrate outside of the sealing material; and
exposing the terminal by removing the removal part along the half cut line,
wherein the removal part is lifted up along the half cut line by emitting a jet of compressed air into between the part of the first substrate with the terminals formed thereon and the removal part.
According to a method for manufacturing a liquid crystal display device of the invention, a half cut line is formed on the second substrate and the removal of the removal part is started with emitting a jet of compressed air into between a part of the first substrate with a terminal formed thereon and the removal part which is a part of the second substrate. Thereby, the removal part is lifted up along the half cut line and at the same time liquid crystal material, which has been infiltrated into the terminal part when the liquid crystal material is injected, can be blown off. Accordingly, the first and second substrates can be prevented from being closely contacted each other by the liquid crystal material.
In the method of the invention it is preferable that the removal part is completely removed by inserting removal part removing means between a part of the first substrate with terminals formed thereon and the removal part.
According to the invention, the removal part removing means is inserted between a part of the first substrate with the terminal formed thereon and the removal part, which removal part removing means lifts up the removal part so that a jet of compressed air can lift up the removal part, thereby the removal part can be easily removed. At this time, since the removal part is lifted up by the compressed air, the removal part removing means can be easily inserted between the first substrate and the removal part.
In the method of the invention it is preferable that the compressed air is emitted as a jet in the diagonal direction toward the liquid crystal display device instead of in the opposite direction to the insertion of the removal part removing means.
According to the invention, by emitting compressed air as a jet in the diagonal direction toward the liquid crystal display device instead of in the opposite direction to the insertion of the removal part removing means, the compressed air is emitted as a jet from diagonally behind the removal part removing means so that the removal part removing means can remove the removal part with an aid of the compressed air.
In the method of the invention it is preferable that the first and second substrates are made of thermoplastic resin.
According to the invention, the removal part can be easily removed even in the case where the first and second substrates are made of thermoplastic resin.
In the method of the invention it is preferable that the jet of compressed air is emitted under the condition that at least a part, on which a layer of the sealing material is formed in the vicinity of the half cut line, is pressed down.
According to the invention, in the method for manufacturing a liquid crystal display device, a part, on which a layer of the sealing material is provided in the vicinity of the half cut line within the liquid crystal display device, is pressed down so that the liquid crystal display device is secured while a jet of compressed air is being emitted. Thereby the display surface of the liquid crystal display device is not pressed without damaging the display quality of the liquid crystal display device, and the sealing material can be prevented from being pealed off from the substrate while the removal part is being removed.
The invention provides an apparatus for removing a removal part from a liquid crystal display device manufactured by a process comprising providing a first substrate on which terminals and display electrodes are formed and a second substrate on which display electrodes are formed; bonding the first substrate and the second substrate to each other via a sealing material at a bonding region which is provided along an outer periphery of the substrates so as not to surround the terminals, so that the display electrodes face each other; forming a display part by injecting a liquid crystal material in a space enclosed by the sealing material and the substrates; providing a half cut line along a border of a removal part which is a part of the second substrate and faces the terminals on a part of the first substrate outside of the sealing material; and exposing the terminals by removing the removal part along the half cut line,
the apparatus comprising:
means for sucking the liquid crystal display device onto a suction stage; and
means for supplying compressed air into between the removal part of the liquid crystal display device and the first substrate.
According to the invention, an apparatus for removing a removal part removes the removal part, which is a part facing a terminal within the second substrate, from a liquid crystal display device which is formed by sealing liquid material between the first substrate, on which a display electrode and a terminal are formed, and the second substrate, on which a display electrode is formed. Thereby, the apparatus for removing the removal part sucks the liquid crystal display device onto a suction stage after a half cut line is provided along a border of the removal part on the second substrate, and supplies compressed air between the removal part and the first substrate. As a result, the removal part is lifted up by the compressed air so that the liquid crystal material, which has been infiltrated between the removal part and the first substrate, is blown off, therefore the terminal can be easily exposed without fail.
In the apparatus of the invention it is preferable that the apparatus further comprises securing means for securing the second substrate of the liquid crystal display device.
According to the invention, the apparatus for removing a removal part further uses not only a suction stage but also a securing means for securing the second substrate, at the time a jet of compressed air is emitted, so that the liquid crystal display device is secured. Thereby, the apparatus for removing a removal part can lift up only the removal part by using compressed air.
In the apparatus of the invention it is preferable that the apparatus further comprises a removal head for contacting the removal part to remove the removal part from the liquid crystal display device.
According to the invention, the apparatus for removing a removal part removes the removal part by using not only compressed air but also a removal head. Since the removal part is lifted up by compressed air, it becomes possible to easily insert the removal head into between the removal part and the first substrate so that only the removal part is contacted. Thereby the apparatus for removing a removal part can surely remove the removal part without damaging the terminal.